CGC Sheetrock® 20 Setting-Type Joint Compound Coverage: Approx. 430 sq. ft. per bag (52 lbs. per 1000 sq. ft.). Setting Time: 20-30 minutes. Application: As an Interior/Exterior joint compound, a laminating agent, as well as filling, smoothing and finishing concrete ceilings. CGC Sheetrock® 20 Setting-Type Joint Compound is a chemically setting powder, when mixed with water, for same day joint finishing and next day decorating. It's unique formulation provides a lightweight product that's easily mixed, applied and sanded to a smooth finish. Sheetrock® 20 is unaffected by humidity and bonds with little shrinkage. Data Sheet